To set the best MTU value and optimize Internet speed, please perform the following steps:
1 Open “Terminal“
2 Type the command below and hit enter.
ping –c 3 –D –s 1500 google.com
If the reply you get is “ping: sendto: Message too long”, then you have to try a lower MTU value. Keep decreasing the value by 10, i.e. 1490, 1480, 1470 until you get a successful reply.
3 Start increasing the MTU value with small increments after you get a successful reply. Eventually, you will arrive on a value on which packets will not fragment, add 28 to that value (IP / ICMP headers).
For instance, if you got the last successful reply on 1470, then add 28 to it, 1470+28 = 1498.
4 This number is your MTU value.
5 Click the “Apple” icon located at the top left corner of your screen and select “System Preferences…”.
6 Click “Network”
7 Select active internet connection i.e. Ethernet or Wifi and click “Advanced…”
8 Click “Hardware” and select “Manually” from the “Configure” drop down menu.
9 Select “Custom” from the MTU drop down menu.
10 Input the MTU value here, and click “OK” and “Apply”.
Recommended: For VPN connection please try MTU 1200